1. Field of the Invention
The present invention relates to a toner cartridge, and a process unit and image forming apparatus using the same. In particular, the invention relates to the toner cartridge used for an image forming apparatus by means of toner, and a process unit and image forming apparatus using the same.
2. Description of the Related Art
The image forming apparatus such as a copier and a facsimile apparatus is designed for continuously operating output of images by supplying a developing apparatus with the toner by a toner replenishing apparatus using such as the toner cartridge.
Recently, as a toner replenishing method to the developing apparatus, a method that replaces an empty toner cartridge with a new one becomes mainstream, instead of a method that replenishes the toner from a toner container to a toner hopper. According to this method, it is possible to supply the toner without smearing an operator's hands.
However, in such a toner cartridge, there may arise a problem that the toner is aggregated to one another and solidified due to its own weight and, as a consequence, cannot be smoothly replenished to the inner portion of the image forming apparatus. In addition, a toner cartridge provided with an agitating propeller in the toner cartridge for agitating the toner is known, but this type of toner cartridge is rather expensive.
In order to solve such a problem, Japanese Unexamined Patent Publication JP-A 2004-271995 discloses a toner cartridge which has a cylindrical shape with a bottom and a spiral projection which is formed on an inner surface of the toner cartridge and projects inward. The toner cartridge disclosed in JP-A 2004-271995 rotates about its axis in the image forming apparatus for conveying the toner by the spiral projection and feeding the toner to the main body of the image forming apparatus.
According to this method, it is possible with a low-cost apparatus configuration to prevent aggregation of the toner in the toner cartridge and to supply the toner smoothly. Further, this toner cartridge can be rotated by supplying a driving force from an end thereof. Therefore, with this toner cartridge, a toner replenishing apparatus that suppress the toner aggregation can be obtained without a complicated toner agitating mechanism.
However, the toner cartridge disclosed in JP-A 2004-271995 has a problem that the toner adheres to and remain unfed around the projection (hereinafter, referred to as toner guide projection) which is provided, as a means to convey the toner toward a toner discharging port, at an inner wall of the toner cartridge and formed in spirals.
In particular, when the quantity of toner in the toner cartridge is decreased, there may arise a problem described below. The toner cartridge has two concavities (back sides of the toner guide projection) therein composed across a base part of the projection. The toner easily adheres to a more distant concavity from the toner discharging port (a concavity disposed at upstream side of toner conveying direction) because the toner rarely contacts with (is rubbed by) toner in fluidized state. As a result, the quantity of the toner remains unfed is increased.